Dopamine D2 up-regulation in psychosis patients after antipsychotic drug treatment.

PURPOSE OF REVIEW

Recently, it has been questioned whether the re-emergence of psychotic symptoms following antipsychotic discontinuation or dose reduction is attributable to underlying psychotic vulnerability or to rebound effects of chronic use of antipsychotic medication. It was repeatedly shown that relapse rates are high after discontinuation of maintenance treatment. A potential contributing factor could be the increase in density of postsynaptic dopamine D2 receptors in the striatum and the higher affinity of D2 receptors for dopamine after chronic blockade.

RECENT FINDINGS

To date, little clinical evidence is available for the mechanisms involved in postsynaptic striatal D2 receptor up-regulation after use of antipsychotic medication, and most knowledge comes from animal studies.

SUMMARY

Further research is needed to investigate whether antipsychotic medication causes neuroadaptations leading to a dopamine supersensitive state in humans, how long such hypersensitive states may last and what differences exist between high and low D2 affinity antipsychotic drugs. Further, information is needed on discontinuation schedules that provide optimal protection for relapse during hypersensitive periods.